NinePatch or .9 PNG files are a nuisance for many. These awkward little blighters are the number one cause of Android themers throwing their PC out of the window. Despite being incredibly frustrating, once mastered they are also incredibly useful and allow the use of a single image in various different shapes and sizes. Getting to grips with them can take a little time though and there are various tools out there to help. If you’re just starting out with these particular files, there’s no better place to start than a good old fashioned tutorial.
XDA Recognized Contributor iamareebjamal put together an incredibly detailed (and I mean incredibly detailed) guide to NinePatch files. The guide takes you through the process of decompiling and editing them, along with a rundown of all the tools you will need to do so. As an added bonus, it also covers some of the most commonly themed areas of the UI and where to find the relevant image files as well as how to edit a batch of PNG files at once.
Packed with screenshots and information, this guide is well worth a look for anyone getting to grips with Android theming. Even those who have been theming for a while might learn a thing or two from this one. You can find more in the tutorial thread._________